1. Field of the Invention
The present invention relates to a a stitch balancing thread tension device for a sewing machine.
2. Description of the Related Art
As a conventional stitch balancing thread tension device (referred to as a thread tension device hereinafter) for a sewing machine, there is known a thread tension device which is attached to a sewing machine body 58 composed of the casing or front cover thereof as illustrated in FIG. 5. The thread tension device 50 is attached to the sewing machine body according to the following process. That is, a stem 51 of the thread tension device body is inserted into the opening portion 58a of the sewing machine body 58 until an annular projecting portion 52 is brought into contact with the outer side surface 58b of the sewing machine body 58, and a nut 55 is screwed thereon after setting a washer 53 and a spring washer 54 onto the externally threaded stem 51.
In this way the thread tension device 50 is attached to the sewing machine body 58 as the latter is clamped between the annular projecting portion 52 and the nut 55. The thus attached thread tension device 50 elastically clamps a needle thread, not shown, between a pair of thread tension discs 56a and 56b for applying a given tension thereto. A projection 52a formed on the projecting portion 52 engages a retaining hole 58d on the sewing machine body 58 for preventing the stem 51 from turning. A regulating dial 57 comprises a tension spring, not shown, therein for bringing the pair of tension discs 56a and 56b into elastic contact with each other.
Such a conventional thread tension device 50, however, had a technical problem created by troublesome operations in attaching the device to the machine body and in detaching the device from the machine body.